Image pickup system including image pickup device and connection device for connecting to external display device

ABSTRACT

An image pickup system including an image pickup device and a connection device is provided. The image pickup device includes an image pickup unit which picks up a subject image, a display unit, a first character image generation unit, and a first control unit. The first character image generation unit generates a first character image representing one or more characters to be displayed on the display unit. The first control unit outputs the subject image and information representing the above-noted one or more characters to the connection device when the image pick-up device and the connection device are connected with each other. The connection device includes a second character image generation unit. The second character image generation unit generates a second character image representing one or more characters to be displayed on an external display device, based on the information representing the above-noted one or more characters.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image pickup system including animage pickup device such as a digital camera (electronic camera) and aconnection device connectable thereto, and more particularly to an imagepickup system for connecting an image pickup device to an externaldisplay device through a connection device.

2. Description of the Related Art

A connection device is conventionally used which is called a cradle forcharging a battery contained in an electronic camera and for connectingthe electronic camera to an external device or a network. For example, acradle is used to allow external display equipment to display an imageof a subject that is generated by an electronic camera.

Usually, a date and a menu screen in addition to a subject image can bedisplayed on a monitor of an electronic camera. When an electroniccamera is connected to external display equipment through a cradle, suchinformation is also displayed on the external display equipment. In theconventional electronic camera, however, the characters displayed on themonitor unit of the electronic camera are enlarged and displayed as theyare on the external display equipment. Therefore, illegible,low-resolution characters are displayed on the external displayequipment.

SUMMARY OF THE INVENTION

In an aspect, the present invention provides an image pickup systemincluding an image pickup device and a connection device connectable tothe image pickup device. The image pickup device includes an imagepickup unit which picks up a subject image, a display unit, a firstcharacter image generation unit, and a first control unit. The firstcharacter image generation unit generates a first character imagerepresenting one or more characters. The first control unit allows thedisplay unit to display the subject image, the first character image, ora combined image of the subject image with the first character image,when a connected state in which the image pickup device and theconnection device are connected with each other is not established. Thefirst control unit outputs the subject image and informationrepresenting the above-noted one or more characters to the connectiondevice when the connected state is established. The connection deviceincludes a second character image generation unit and a second controlunit. The second character image generation unit generates a secondcharacter image representing one or more characters based on theinformation representing one or more characters received from the imagepickup device when the connected state is established. The secondcontrol unit allows an external display device to display the subjectimage received from the image pickup device when the connected state isestablished, the second character image, or a combined image of thesubject image with the second character image.

Preferably, a total number of pixels of the external display device isgreater than a total number of pixels of the display unit, and aresolution of the second character image is higher than a resolution ofthe first character image.

Preferably, the image pickup device further includes an operation unitwhich accepts selection of one of first and second display modes from auser. In this case, the first control unit allows the display unit todisplay the subject image when the first display mode is selected andthe connected state is not established. The first control unit outputsthe subject image to the connection device when the first display modeis selected and the connected state is established. The first controlunit allows the display unit to display a combined image of the subjectimage with the first character image when the second display mode isselected and the connected state is not established. The first controlunit outputs the subject image and information representing theabove-noted one or more characters to the connection device when thesecond display mode is selected and the connected state is established.The second control unit outputs the subject image to the externaldisplay device when the first display mode is selected and the connectedstate is established. The second control unit outputs a combined imageof the subject image with the second character image to the externaldisplay device when the second display mode is selected and theconnected state is established.

Preferably, the information representing one or more characters is oneor more character codes respectively corresponding to one or morecharacters.

Preferably, the connection device is connected to an external powersupply. The image pickup device further includes a power supply nodereceiving electric power supplied from the external power supply throughthe connection device when the connected state is established, and avoltage detection unit which detects a value of voltage applied to thepower supply node. In this case, the first control unit senses that theconnected state is established, based on that the value of voltagedetected by the voltage detection unit reaches a prescribed referencevalue.

Preferably, the image pickup device further includes a storage unitwhich stores a subject image when the image pickup unit picks up animage of the subject. In this case, the above-noted one or morecharacters are information related to the subject image. The storageunit stores the information representing one or more characters togetherwith the subject image related thereto when the image pickup unit picksup an image of the subject. The first control unit reads the relatedinformation representing one or more characters together with thesubject image from the storage unit. The first control unit allows thefirst character image generation unit to generate the first characterimage corresponding to the information representing one or morecharacters read from the storage unit when the connected state is notestablished, and outputs the information representing one or morecharacters read from the storage unit to the connection device when theconnected state is established.

In another aspect of the present invention, the image pickup deviceincludes an image pickup unit which picks up a subject image, a displayunit, an operation unit, a first storage unit, and a first control unit.The operation unit accepts selection of one menu from a plurality ofpreset menus, from a user. The first storage unit stores a plurality offirst display images preset respectively corresponding to the pluralityof menus. The first control unit allows the display unit to display thesubject image when a connected state in which the image pickup deviceand the connection device are connected with each other is notestablished and when a selected state in which a menu is selected by theuser is not established. The first control unit allows the display unitto display a first display image corresponding to a menu selected by theuser or a combined image of the subject image with a first display imagecorresponding to a menu selected by the user when the connected state isnot established and the selected state is established. The first controlunit outputs the subject image to the connection device when theconnected state is established. The first control unit outputsinformation of a menu selected by the user to the connection device whenthe connected state is established and the selected state isestablished. The connection device includes a second storage unit and asecond control unit. The second storage unit stores a plurality ofsecond display images preset respectively corresponding to the pluralityof menus. The second control unit allows an external display device todisplay the subject image received from the image pickup device when theconnected state is established and the selected state is notestablished. The second control unit allows the external display deviceto display a second display image corresponding to information of a menuselected by the user that is received from the image pickup device or acombined image of the subject image with a second display imagecorresponding to information of a menu selected by the user when theconnected state is established and the selected state is established.

Preferably, a total number of pixels of the external display device isgreater than a total number of pixels of the display unit, and aresolution of each of the plurality of second display images is higherthan a resolution of each of the plurality of first display images.

In a further aspect of the present invention, the image pickup deviceincludes an image pickup unit which picks up a subject image, a displayunit, a first character image generation unit, and a first control unit.The first character image generation unit generates a first characterimage representing one or more characters based on related informationrelated to the subject image. The first control unit allows the displayunit to display the subject image, the first character image, or acombined image of the subject image with the first character image whena connected state in which the image pickup device and the connectiondevice are connected with each other is not established. The firstcontrol unit outputs the subject image and the related information tothe connection device when the connected state is established. Theconnection device includes a second character image generation unit anda second control unit. The second character image generation unitgenerates a second character image representing one or more charactersbased on the related information received from the image pickup devicewhen the connected state is established. The second control unit allowsan external display device to display the subject image received fromthe image pickup device when the connected state is established, thesecond character image, or a combined image of the subject image withthe second character image. Here, a total number of pixels of theexternal display device is greater than a total number of pixels of thedisplay unit. A resolution of the second character image is higher thana resolution of the first character image.

In accordance with the present invention as described above, when anelectronic camera (image pickup device) is connected to a cradle(connection device), information related to a subject image, such asdate and time, or a menu screen is not added to the subject image in theelectronic camera, while a high-resolution image representing the samecontents is generated in the cradle and then output to external displayequipment. Therefore, the main advantage of the present invention is inthat a character or a character string displayed on a display unit of anelectronic camera can also be displayed at high resolution on anexternal display device.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view showing that an image pickup system inaccordance with an embodiment of the present invention is connected toexternal display equipment.

FIG. 2 is a block diagram showing a configuration of an electroniccamera and a cradle that form the image pickup system in FIG. 1.

FIG. 3 is a flowchart illustrating an exemplary operation of the imagepickup system in FIG. 2.

FIG. 4 shows an example of a character string displayed together with asubject image on external display equipment (in the case where an imagedisplayed on a monitor unit of the electronic camera is enlarged anddisplayed on external display equipment).

FIG. 5 shows an example of a character string displayed together with asubject image on external display equipment (in the case of the imagepickup system in the present embodiment).

FIG. 6 is a flowchart illustrating another exemplary operation of theimage pickup system in FIG. 2.

FIG. 7 shows an example of a menu displayed on external displayequipment (in the case where an image displayed on the monitor unit ofthe electronic camera is enlarged and displayed).

FIG. 8 shows an example of a menu displayed on external displayequipment (in the case of the image pickup system in the presentembodiment).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following embodiment, an image pickup system formed of anelectronic camera and a cradle will be described as an example of imagepickup system.

Referring to FIG. 1, an image pickup system 100 in accordance with anembodiment of the present invention is configured with an electroniccamera 10 and a cradle 50 on which electronic camera 10 is placed.Electronic camera 10 outputs image data to external display equipment 90through cradle 50.

FIG. 2 is a block diagram showing a configuration of electronic camera10 and cradle 50. Referring to FIG. 2, electronic camera 10 includes animage pickup lens 2, a CMOS (Complementary Metal-Oxide Semiconductor)image sensor 6, an image pickup processing unit 8, a CPU (CentralProcessing Unit) 26, a communication input/output terminal 10A, a videooutput terminal 10B, an operation unit 24, an SDRAM (Synchronous DynamicRandom Access Memory) 14, a compression/decompression processing unit28, a data processing unit 20, a character generation unit 30, a flashmemory 12, a card control unit 16, a memory card 18, a video encoder 32,a switch 101, and a monitor unit 4. CPU 26 and data processing unit 20form a first control unit 40.

Image pickup lens 2 forms an optical image of a subject on an imagepickup surface of CMOS image sensor 6 serving as an image pickup device.A digital image pickup signal output from CMOS image sensor 6 isprocessed by image pickup processing unit 8 and converted into a Ysignal that is a luminance signal and a U, V signal that is a colordifference signal. The position in optical axis direction of imagepickup lens 2 is adjusted based on an output signal of CMOS image sensor6.

CPU 26 is connected with image pickup processing unit 8, communicationinput/output terminal 10A, SDRAM 14, compression/decompressionprocessing unit 28, data processing unit 20, character generation unit30, flash memory 12, card control unit 16, and the input node of videoencoder 32, through a bus 34. The output node of video encoder 32 isconnected to switch 101. Switch 101 has output terminals 101A, 101B,101C. Output terminal 101B is connected to video output terminal 10B ofelectronic camera 10, and output terminal 101A is connected to monitorunit 4.

CPU 26 controls image pickup processing unit 8, SDRAM 14,compression/decompression processing unit 28, data processing unit 20,character generation unit 30, flash memory 12, card control unit 16, andvideo encoder 32, in accordance with a program stored in flash memory12. Card control unit 16 is connected to memory card 18 to control datawrite into memory card 18 and data read from memory card 18 inaccordance with an instruction from CPU 26.

In response to an operation on operation unit 24 by the user, an imagepickup process and a replay process are executed by CPU 26. The user canselect one of a plurality of preset operations using operation unit 24.

Specifically speaking of the image pickup process, CPU 26 compresses thepicked-up moving images or still image by compression/decompressionprocessing unit 28. CPU 26 thereafter controls card control unit 16 suchthat the compressed moving image data or still image data is recorded asa moving image file or a still image file in memory card 18. Here, CPU26 also allows information related to a subject image (hereinafterreferred to as “related information”), such as a shooting date, ashooting time, and a file name, to be recorded in memory card 18. Forexample, when a date as an example of related information is recorded inmemory card 18, it may be recorded as a plurality of character codes(ASCII codes, for example) or as a numeric string (binary data)representing year, month and day.

Specifically speaking of the replay process, CPU 26 reads a moving imagefile or a still image file recorded in memory card 18 and decompressesthe read file into original image data by compression/decompressionprocessing unit 28. The related information recoded in memory card 18 isalso read from memory card 18 together with the image file. CPU 26thereafter converts the decompressed image data into an analog videosignal by video encoder 32 and outputs the converted analog video signalto monitor unit 4 or video output terminal 10B through switch 101. SDRAM14 is used to temporarily store data in such image pickup process andreplay process.

The related information related to a subject image that is recorded inmemory card 18 can also be displayed on monitor unit 4 of electroniccamera 10. In this case, at least part of the related information may beconverted into an image and combined with the subject image and thendisplayed on monitor unit 4. Alternatively, only the related informationmay be displayed apart from the subject image on monitor unit 4, as isthe case where, for example, a list of file names recorded in memorycard 18 is displayed on monitor unit 4.

In the case where at least part of the related information recorded inmemory card 18 is displayed on monitor unit 4, character generation unit30 generates an image (referred to as “character image”) correspondingto a character string representing the related information to bedisplayed, using font data stored beforehand in flash memory 12. Data ofbitmap fonts, outline fonts, and the like may be used as font data. Theresolution of the generated character image varies depending on thetotal number of pixels of monitor unit 4.

CPU 26 thereafter adds the character image generated by charactergeneration unit 30 to the analog video signal converted by video encoder32, in accordance with a prescribed operation on operation unit 24. Inthis case, the analog video signal is first stored in data processingunit 20 and the character image is then added to the stored analog videosignal. In the case where the related information alone is displayed onmonitor unit 4, CPU 26 replaces the analog video signal stored in dataprocessing unit 20 with the character image generated by charactergeneration unit 30.

In order to output data from electronic camera 10 to cradle 50,electronic camera 10 is provided with communication input/outputterminal 10A and video output terminal 10B. Communication input/outputterminal 10A is connected to CPU 26 of electronic camera 10. Relatedinformation related to a subject image, such as a shooting data, as wellas a control signal is output from communication input/output terminal10A to cradle 50. An analog video signal is output from video outputterminal 10B to cradle 50.

Cradle 50 includes a microcomputer 52, a character generation unit 54, aflash memory 58, a data processing unit 60, and a video encoder 56.Microcomputer 52 and data processing unit 60 form a second control unit70. Cradle 50 further includes a communication input/output terminal 50Aand a video input terminal 50B for connecting to communicationinput/output terminal 10A and video output terminal 10B, respectively.Microcomputer 52 is connected to communication input/output terminal50A.

Cradle 50 further includes a video output terminal 50C. Video outputterminal 50C can connect to external display equipment 90. Externaldisplay equipment 90 has more total pixels than monitor unit 4 ofelectronic camera 10. Video output terminal 50C is connected to videoencoder 56 of cradle 50.

Microcomputer 52 is connected to video input terminal 50B, dataprocessing unit 60, character generation unit 54, flash memory 58, andvideo encoder 56 through a bus 62.

Microcomputer 52 controls data processing unit 60, character generationunit 54, flash memory 58, and video encoder 56 in accordance with aprogram stored in flash memory 58.

In the case where at least part of related information such as ashooting date and time is displayed on external display equipment 90,microcomputer 52 allows character generation unit 54 to generate acharacter image corresponding to a character string representing therelated information to be displayed on external display equipment 90,based on the related information received from electronic camera 10.Here, character generation unit 54 generates a character image accordingto the total number of pixels of external display equipment 90 based onthe font data stored beforehand in flash memory 58. Data of bitmapfonts, outline fonts, and the like can be used as font data.

Microcomputer 52 adds the character image generated in charactergeneration unit 54 to the analog video signal input from video inputterminal 50B. In this case, the analog video signal is first stored indata processing unit 60 and the character image is then added to thestored analog video signal. In the case where the character image aloneis displayed on external display equipment 90, microcomputer 52 replacesthe analog video signal stored in data processing unit 60 with thecharacter image generated in character generation unit 54. Video encoder56 converts the output data of data processing unit 60 into an analogvideo signal for output to external display equipment 90.

Electronic camera 10 further includes a power supply terminal 10D, abattery 36 for driving electronic camera 10, and a voltage detectionunit 38. Cradle 50 further includes a power supply terminal 50Dconnected to power supply terminal 10D of electronic camera 10. Cradle50 is connected to an external power supply 80. Electronic camera 10receives electric power supplied from external power supply 80 throughpower supply terminals 10D and 50D when it is connected to cradle 50.Accordingly, battery 36 is charged. Voltage detection unit 38 detectsvoltage of power supply terminal 10D. CPU 26 senses that electroniccamera 10 and cradle 50 are in the connected state based on that aprescribed reference voltage is detected by voltage detection unit 38.

Referring now to the block diagram in FIG. 2 and the flowchart in FIG.3, an exemplary operation of image pickup system 100 in FIG. 2 will bedescribed. FIG. 3 shows an operation of image pickup system 100 in thecase where only a subject image is displayed on external displayequipment 90 and in the case where a subject image is combined with animage representing a shooting date or a shooting time related theretoand then displayed on external display equipment 90.

First, in step S102, CPU 26 contained in electronic camera 10 determineswhether or not electronic camera 10 is connected to cradle 50. If CPU 26determines NO (not-connected state), the process in step S102 isrepeated. If CPU 26 determines YES (connected state), the processproceeds to step S104. In step S104, CPU 26 starts communication withmicrocomputer 52 contained in cradle 50.

Then, in step S106, CPU 26 determines whether or not the display mode isset such that the related shooting date, shooting time, and the like isdisplayed together with a subject image on monitor unit 4 or externaldisplay equipment 90. The settings of display modes are stored in flashmemory 12 of electronic camera 10, and the initial setting is set to amode of displaying only a subject image. The user can select a displaymode by operating operation unit 24.

If CPU 26 determines NO in step S106, the process proceeds to step S116.In step S116, CPU 26 switches the output terminal of switch 101 fromterminal 101A to terminal 101B. Accordingly, the output destination ofthe analog video signal to which the image representing a shooting date,a shooting time, and the like is not added is switched from monitor unit4 to cradle 50. Microcomputer 52 contained in cradle 50 outputs theanalog video signal output from video output terminal 10B of electroniccamera 10, from video output terminal 50C of cradle 50 to externaldisplay equipment 90. The subject image is thereafter displayed onexternal display equipment 90.

If CPU 26 determines YES in step S106, the process proceeds to stepS108. In step S108, CPU 26 switches the output terminal of switch 101from terminal 101A to terminal 101C located between terminal 101A andterminal 101B and turns off the video output to monitor unit 4 ofelectronic camera 10.

Then, in step S110, CPU 26 prohibits the character image generated incharacter generation unit 30 of electronic camera 10 from being added tothe analog video signal. CPU 26 outputs information (for example,character codes) representing a character or a character string to bedisplayed on external display equipment 90, to cradle 50 throughcommunication input/output terminal 10A.

Then, in step S112, CPU 26 switches the output terminal of switch 101from terminal 101C to terminal 101B. Accordingly, the analog videosignal to which information such as a date is not added is input fromvideo output terminal 10B of electronic camera 10 to video inputterminal SOB of cradle 50. The input analog video signal is temporarilystored by data processing unit 60 of cradle 50.

In the next step S114, microcomputer 52 contained in cradle 50 allowscharacter generation unit 54 of cradle 50 to generate a character imagebased on the information (for example, character codes) representing acharacter or a character string received from electronic camera 10. Dataprocessing unit 60 adds the generated character image to the analogvideo signal based on control of microcomputer 52.

Then, in step S116, video encoder 56 outputs the video signal to whichthe character image is attached in data processing unit 60, from videooutput terminal 50C of cradle 50 to external display equipment 90. Thevideo signal with the character image added thereto is displayed onexternal display equipment 90.

FIG. 4 and FIG. 5 show an example of a character string displayedtogether with a subject image on external display equipment 90. FIG. 4shows the case where an image displayed on monitor unit 4 of electroniccamera 10 is enlarged and displayed as it is, unlike the presentembodiment. FIG. 5 shows the case of image pickup system 100 of thepresent embodiment. According to image pickup system 100 of the presentembodiment, as illustrated in FIG. 5, the image of the same date asillustrated in FIG. 4 can be displayed at high resolution and at highdefinition.

As described above, conventionally, in the case of electronic camera 10,an image displayed on monitor unit 4 is enlarged and displayed as it ison external display equipment 90. Therefore, a low-resolution andlow-visibility character or character string is displayed on externaldisplay equipment 90. In image pickup system 100 of the presentembodiment, when electronic camera 10 is connected to cradle 50,electronic camera 10 does not add information related to a subjectimage, such as a shooting date and a shooting time, to the subjectimage, but cradle 50 generates a high-resolution character imagerepresenting the same contents and adds the generated character image tothe image data received from electronic camera 10 for output to externaldisplay equipment 90. Accordingly, the high-resolution, fine imagerepresenting a character can be displayed together with the subjectimage on external display equipment 90.

As described above, although cradle 50 is additionally provided with afunction of generating a character image, image data of a subject isreceived as a video signal from electronic camera 10, as isconventionally done. Therefore, the circuit size of cradle 50 is notsignificantly increased as compared with the conventional one.

In the case where only a character image is displayed in place of asubject image, data processing unit 60 replaces the stored analog videosignal with the character image generated in character generation unit54, in the above-noted step S114. Then, in the next step S116, videoencoder 56 reads the character image stored in data processing unit 60for output to external display equipment 90. Accordingly, only thecharacter image can be displayed on external display equipment 90.

Referring now to the block diagram in FIG. 2 and the flowchart in FIG.6, another exemplary operation of image pickup system 100 in FIG. 2 willbe described. FIG. 6 illustrates that an image of a shooting menu asshown in FIG. 7, FIG. 8 is displayed on monitor unit 4 of electroniccamera 10 or external display equipment 90.

An image (also referred to as “display image”) of a menu selected by theuser using operation unit 24 appears on monitor unit 4. The menu isoptions displayed on the screen. Electronic camera 10 is provided withmany menus such as a shooting menu for setting shooting conditions ofthe electronic camera and an image processing menus for processing thepicked-up subject image. The user can select which of a plurality ofmenus is to be displayed on the screen, using operation unit 24, and inaddition, can select an item that he wants to process, among options onthe menu displayed on the screen.

Therefore, in order to display menus on monitor unit 4, a plurality ofdisplay images respectively corresponding to a plurality of menusselectable by the user are stored beforehand in flash memory 12 ofelectronic camera 10. When the user selects a menu using operation unit24, CPU 26 reads the display image corresponding to the selected menufrom flash memory 12 and displays that image on monitor unit 4. Here,the display menu representing the menu that appears on monitor unit 4 isnot limited to characters. For example, in order to select people or ascene as the subject, an icon representing people and an iconrepresenting a scene may be displayed on the screen. The resolution ofthe image such as a shooting menu to be displayed on monitor unit 4 isdetermined according to the total number of pixels of monitor unit 4.

On the other hand, the display image such as a shooting menu to bedisplayed on external display equipment 90 is stored beforehand in flashmemory 58 of cradle 50, corresponding to each of a plurality ofoperations selectable by operation unit 24 of electronic camera 10. Wheninformation of the menu selected by the user is sent to cradle 50 uponconnection between electronic camera 10 and cradle 50, microcomputer 52reads the display image corresponding to the received information of themenu from flash memory 58 and outputs the same to external displayequipment 90. The resolution of the image such as a shooting menu to bedisplayed on external display equipment 90 is higher than that of theimage displayed on monitor unit 4 of electronic camera 10 because it isdetermined by the total number of pixels of external display equipment90.

In the first step S302 in FIG. 6, CPU 26 contained in electronic camera10 determines whether or not electronic camera 10 is connected to cradle50. If CPU 26 determines NO (not-connected state), the process in stepS302 is repeated. If CPU 26 determines YES (connected state), theprocess proceeds to step S304. In step S304, CPU 26 starts communicationwith microcomputer 52 contained in cradle 50.

Then, in step S306, CPU 26 determines whether or not the user isselecting a menu (also referred to as “selected state”) using operationunit 24. If the user is selecting a shooting menu using operation unit24, the image appearing on monitor unit 4 is switched from a subjectimage to an image of the selected shooting menu.

If CPU 26 determines NO in step S306 (not-selected state), the processproceeds to step S316. In step S316, CPU 26 switches the output terminalof switch 101 from terminal 101A to terminal 101B. Accordingly, theanalog video signal that has been output to monitor unit 4 is output tocradle 50. Microcomputer 52 contained in cradle 50 outputs the analogvideo signal received through video output terminal 10B of electroniccamera 10, from video output terminal 50C of cradle 50 to externaldisplay equipment 90. The video signal is thereafter displayed onexternal display equipment 90.

On the other hand, if CPU 26 determines YES (selected state) in stepS306, the process proceeds to step S308. In step S308, CPU 26 switchesthe output terminal of switch 101 from terminal 101A to terminal 101Clocated between terminal 101A and terminal 101B to turn off the videooutput to monitor unit 4 of electronic camera 10.

Then, in step S310, CPU 26 switches the setting so that the image of themenu stored in flash memory 12 is not displayed in place of the analogvideo signal. CPU 26 sends information of the menu selected by operationunit 24 to cradle 50.

Then, in step S312, CPU 26 switches switch 101 from terminal 101C toterminal 101B so that the video signal representing the subject imagethat is before switching to the image of the shooting menu is input fromvideo output terminal 10B to video input terminal 50B of cradle 50. Theinput video signal representing the subject image is temporarily storedby data processing unit 60 of cradle 50.

In the next step S314, microcomputer 52 contained in cradle 50 reads thedisplay image corresponding to the information of the menu received fromelectronic camera 10, from flash memory 58. Data processing unit 60replaces the stored analog video signal representing the subject imagewith the image of the selected shooting menu, in accordance with controlof microcomputer 52.

Then, in step S316, video encoder 56 outputs a signal replaced with theimage of the shooting menu by data processing unit 60 from video outputterminal 50C of cradle 50 to external display equipment 90. As a result,the image of the shooting menu appears on external display equipment 90.

FIG. 7 and FIG. 8 show an example of an image of a shooting menudisplayed on external display equipment 90. FIG. 7 illustrates the casewhere the image displayed on monitor unit 4 of electronic camera 10 isenlarged and displayed as it is, unlike the present embodiment. FIG. 8illustrates the case of image pickup system 100 of the presentembodiment. According to image pickup system 100 of the presentembodiment, as illustrated in FIG. 8, the image representing theshooting menu having the same contents as illustrated in FIG. 7 can bedisplayed at high resolution and at high definition.

As described above, conventionally, an image representing a shootingmenu or the like displayed on monitor unit 4 of electronic camera 10 isenlarged and displayed as it is on external display equipment 90.Therefore, a low-resolution and low-visibility image is displayed onexternal display equipment 90. In image pickup system 100 of the presentembodiment, when electronic camera 10 is connected to cradle 50,information of the menu selected by the user using operation unit 24 issent to cradle 50. In cradle 50, a display image corresponding to thereceived information of the menu is read from flash memory 58 of cradle50 and output to external display equipment 90. As a result, thehigh-resolution, fine image of the shooting menu can be displayed onexternal display equipment 90.

An image of a shooting menu may be combined with a subject image anddisplayed on external display equipment 90. In this case, dataprocessing unit 60 adds the image of the shooting menu read from flashmemory 58 to the analog video signal, in the above-noted step S314. Inthe next step S316, video encoder 56 outputs to external displayequipment 90 the video signal to which the image of the shooting menugenerated by data processing unit 60 is added. Accordingly, the image ofthe shooting menu and the subject image that are combined together aredisplayed on external display equipment 90.

In the foregoing embodiment, the description has been made using animage pickup system formed of an electronic camera and a cradle as anexample in order to facilitate the understanding. It is needless to saythat an image pickup system having any connection device other than acradle may use a similar configuration to display a high-resolution finecharacter or character string on external display equipment.

In the foregoing embodiment, a character string added to a subject imageis a shooting date as in FIG. 4 and FIG. 5. However, the added characterstring is not limited to a shooting date. A variety of character stringssuch as a shooting time and a data file name can be added to a subjectimage. The character string added to a subject image in the electroniccamera may not be the same as that in the cradle. For example, onlymonth and day without year may be displayed as a date on monitor unit 4of electronic camera 10 having a small total number of pixels, whileyear, month and day may be displayed without omitting year on externaldisplay equipment 90.

In the foregoing embodiment, the image of the shooting menu as in FIG. 7and FIG. 8 is displayed in place of a subject image on monitor unit 4 orexternal display equipment 90. However, the displayed menu is notlimited to the shooting menu. A variety of menus such as imageprocessing menus including brightness or contrast change may bedisplayed on monitor unit 4 or external display equipment 90. Thecontent of an image representing a menu that is stored in the flashmemory in the electronic camera may be not be the same as that in thecradle. For example, a more simplified menu may be displayed on monitorunit 4 of electronic camera 10 having a small total number of pixelsthan on external display equipment 90.

In the foregoing embodiment, a CMOS image sensor has been illustrated asan image pickup device. However, the present invention is not limitedthereto, and a similar configuration may be formed with any other imagepickup device, for example, a CCD (Charge-Coupled Device) imager.

Although a memory card has been illustrated as a recording medium in theforegoing embodiment, any other recording medium, for example, a harddisk, may be employed.

In the foregoing embodiment, the connected state between electroniccamera 10 and cradle 50 is sensed based on that voltage detection unit38 provided for electronic camera 10 detects a prescribed voltage basedon external power supply voltage. However, the method for sensing theconnected state is not limited thereto, and the connected state may besensed, for example, based on that a switch provided for cradle 50 isturned on when electronic camera 10 is placed in cradle 50.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present invention being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. An image pickup system comprising: an imagepickup device, and a connection device connectable to said image pickupdevice, said image pickup device including an image pickup unit whichpicks up a subject image, a display unit, a first character imagegeneration unit which generates a first character image representing oneor more characters, and a first control unit which allows said displayunit to display said subject image, said first character image, or acombined image of said subject image with said first character image,when a connected state in which said image pickup device and saidconnection device are connected with each other is not established, saidfirst control unit outputting said subject image and informationrepresenting said one or more characters to said connection device whensaid connected state is established, said connection device including asecond character image generation unit which generates a secondcharacter image representing said one or more characters based on saidinformation representing one or more characters received from said imagepickup device when said connected state is established, and a secondcontrol unit which allows an external display device to display saidsubject image received from said image pickup device when said connectedstate is established, said second character image, or a combined imageof said subject image with said second character image.
 2. The imagepickup system according to claim 1, wherein a total number of pixels ofsaid external display device is greater than a total number of pixels ofsaid display unit, and a resolution of said second character image ishigher than a resolution of said first character image.
 3. The imagepickup system according to claim 2, wherein said image pickup devicefurther includes an operation unit which accepts selection of one offirst and second display modes from a user, said first control unitallows said display unit to display said subject image when said firstdisplay mode is selected and said connected state is not established,said first control unit outputs said subject image to said connectiondevice when said first display mode is selected and said connected stateis established, said first control unit allows said display unit todisplay a combined image of said subject image with said first characterimage when said second display mode is selected and said connected stateis not established, said first control unit outputs said subject imageand said information representing one or more characters to saidconnection device when said second display mode is selected and saidconnected state is established, said second control unit outputs saidsubject image to said external display device when said first displaymode is selected and said connected state is established, and saidsecond control unit outputs a combined image of said subject image withsaid second character image to said external display device when saidsecond display mode is selected and said connected state is established.4. The image pickup system according to claim 3, wherein saidinformation representing one or more characters is one or more charactercodes respectively corresponding to said one or more characters.
 5. Theimage pickup system according to claim 3, wherein said connection deviceis connected to an external power supply, said image pickup devicefurther includes a power supply node receiving electric power suppliedfrom said external power supply through said connection device when saidconnected state is established, and a voltage detection unit whichdetects a value of voltage applied to said power supply node, and saidfirst control unit senses that said connected state is established,based on that the value of voltage detected by said voltage detectionunit reaches a prescribed reference value.
 6. The image pickup systemaccording to claim 2, wherein said image pickup device further includesa storage unit which stores a subject image when said image pickup unitpicks up an image of said subject, said one or more characters areinformation related to said subject image, said storage unit stores saidinformation representing one or more characters together with saidsubject image related thereto when said image pickup unit picks up animage of said subject, said first control unit reads related saidinformation representing one or more characters together with saidsubject image from said storage unit, said first control unit allowssaid first character image generation unit to generate said firstcharacter image corresponding to said information representing one ormore characters read from said storage unit when said connected state isnot established, and said first control unit outputs said informationrepresenting one or more characters read from said storage unit to saidconnection device when said connected state is established.
 7. An imagepickup system comprising: an image pickup device, and a connectiondevice connectable to said image pickup device, said image pickup deviceincluding an image pickup unit which picks up a subject image, a displayunit, an operation unit which accepts selection of one menu from aplurality of preset menus, from a user, a first storage unit whichstores a plurality of first display images preset respectivelycorresponding to said plurality of menus, and a first control unit whichallows said display unit to display said subject image when a connectedstate in which said image pickup device and said connection device areconnected with each other is not established and when a selected statein which a menu is selected by said user is not established, and allowssaid display unit to display a first display image corresponding to amenu selected by said user or a combined image of said subject imagewith a first display image corresponding to a menu selected by said userwhen said connected state is not established and said selected state isestablished, said first control unit outputting said subject image tosaid connection device when said connected state is established, andsaid first control unit outputting information of a menu selected bysaid user to said connection device when said connected state isestablished and said selected state is established, said connectiondevice including a second storage unit which stores a plurality ofsecond display images preset respectively corresponding to saidplurality of menus, and a second control unit which allows an externaldisplay device to display said subject image received from said imagepickup device when said connected state is established and said selectedstate is not established, and allows said external display device todisplay a second display image corresponding to information of a menuselected by said user that is received from said image pickup device ora combined image of said subject image with a second display imagecorresponding to information of a menu selected by said user when saidconnected state is established and said selected state is established.8. The image pickup system according to claim 7, wherein a total numberof pixels of said external display device is greater than a total numberof pixels of said display unit, and a resolution of each of saidplurality of second display images is higher than a resolution of eachof said plurality of first display images.
 9. An image pickup systemcomprising: an image pickup device, and a connection device connectableto said image pickup device, said image pickup device including an imagepickup unit which picks up a subject image, a display unit, a firstcharacter image generation unit which generates a first character imagerepresenting one or more characters based on related information relatedto said subject image, and a first control unit which allows saiddisplay unit to display said subject image, said first character image,or a combined image of said subject image with said first characterimage when a connected state in which said image pickup device and saidconnection device are connected with each other is not established, saidfirst control unit outputting said subject image and said relatedinformation to said connection device when said connected state isestablished, said connection device including a second character imagegeneration unit which generates a second character image representingone or more characters based on said related information received fromsaid image pickup device when said connected state is established, and asecond control unit which allows an external display device to displaysaid subject image received from said image pickup device when saidconnected state is established, said second character image, or acombined image of said subject image with said second character image,wherein a total number of pixels of said external display device isgreater than a total number of pixels of said display unit, and aresolution of said second character image is higher than a resolution ofsaid first character image.